Atomizer for liquid fuel



Jan. 8, 1963 R. D. REED ATOMIZER FOR LIQUID FUEL Filed April 19, 1961 United Stats The present invention relates to a device for breaking liquid fuel into micron-size particles of substantially uniform size to facilitate mixture of the small size fuel droplets with air prior to delivery of such a fuel mixture to a zone of combustion. The invention more specifrcally pertains to structural characteristics which cooperate to produce a spinning of the liquid fuel without mechanically moving parts and the spinning liquid is released as a generally conical shaped spray providing a preliminary atomization prior to the action of steam or compressed air.

In many of the prior devices the liquid fuel is delivered to the presence of steam or compressed air as an unbroken liquid. The steamer air serves the function of breaking the liquid into drops but such devices do not producesmall droplets of uniform size by the time the fuel mixture is delivered into the zone of combustion. Variations in the size of the drops produces incomplete combustion and smoke. The drops of liquid fuel which are toolarge to be vaporized escape from the body of the flame and'appear as sparlcs of still burning liquid fuel. When these unburned globules of fuel engage a heat transfer surface or a wall ofthe furnace deposits are formed.

it is accordingly an object of the invention to provide an atomizer wherein the liquid fuel is broken into small droplets before the liquid fuel is subjected to the action ofsteam or compressed air whereby substantially micronsiz'e particles are produced of substantially uniform size which are capable of virtually complete vaporization within the time interval prior to delivery into the zone of combustion.

The prior devices function reasonably well in association with a fuel burner when it is operated throughout a limited range of firing but such an assembly is not satisfactory when the turn down ratio exceeds ten to one. In other words when a burner equipped with a conventional atomizer is fired to release ten million British thermal units per hour and is turned down to release but one million British thermal units per hour the operation is not satisfactory.

It is another object ofthe present invention to provide 'a device for breaking the oil into small droplets so as to reduce the time interval required for conversion of the liquid fuel into agas by vaporization so that the gaseous mixture delivered into the zone of combustion provide a fuel which makes 'it possible to adjust the range of firing of the burner from one hundred percent to about six percent of its rating to thereby provide a turn down ratio for the assembly of approximately sixteen to one.

A more specific object of the invention, is to provide a chamber'having at least one port disposed in tangential or chord position with respect to the axis of the chamber through which the liquid fuel is delivered at a velocity to set up centrifugal force acting on the liquid within the chamber whereby it whirls in a generally helical path in proceeding downstream on the wall of the chamber and escapes at the downstream end thereof as a substantially conical spray of small droplets before being subjected to the action of a gaseous medium which converts the already small droplets, into particles of micronsize and of substantially uniform size to facilitate and accelerate the conversion of the liquid fuel into a gaseous fuel mixture. 7

Other objects and features of the invention will be atent i atented Jan. 8, 1963 as of FIG. 2.

FIG. 4 is a transverse sectional view taken on the line 4-4 of FIG. 2.

FIG. 5 is a section taken on the line 5-5 of FIG. 2.

FIG. 6 is a view similar to FIG. 4 showing a modified disposition of the holes for the steam or air.

FIG. 7 is a fragmentary sectional view diagrammatically illustrating the manner in which the liquid is spilled from the annular chamber.

A feature of the invention as will be apparent as the detailed description of the structure proceeds is that it provides for the disintegration of the liquid fuel into a multitude of small droplets prior to being subjected tov action of steam or compressed air and without action of mechanically moving parts. The liquid fuel after being broken into small particles is subjected to the action of steam or air to develop droplets of uniformly small size which readily vaporize to provide a fuel mixture. which serves to provide stable combustion.

A structural assembly exhibiting the invention is shown in the drawing and it includes a discharge nozzle or tip 10. The nozzle portion may be formed of bar stock having a generally cylindrical interior ill. The forward portion of the nozzle It) is conically shaped and provided with a plurality of discharge ports 12. The exterior of the tip it) has fiat sides to facilitate the threading into a sleeve 14 which may have flat exterior surfaces. The sleeve 14 carries interior threads rs for engaging threads on the exterior of a reduced diameter portion of the tip 10. A suitable seal 17 may be provided between the sleeve 14 and the nozzle ill.

A tubular member 18 is arranged with-in the '--ssembly. It is provided with an exterior annular surface 19 which fits snugly within the interior of the nozzle member The juncture of the tubular member its with the nozzle is a slip fit which avoids leakage from the assembly but permit-s expansion or contraction between the associated parts of the assembly.

The invention includes means for closing the tubular member 18 and such means may take the form of a body member or plug element 21. The body member 231. has an annular exterior surface at the forward end carrying threads which engage threads on the interior of the tubular member 18. The rear portion of the plug element 21 is of smaller cross section than the forward portion and may be rectangular in shape as shown in PEG. 3. The flat faces on the rear portion 22 of the body member facilihates the threading thereof into the tubular member iii. A feature of the invention pertains to the characteristics of a cavity 23 within the body member 21. The cavity 23 is cylindrical shaped and its axis coincides with that of the tubular member 18. The downstream and of the cavity 23 terminates in an annular sharp corner 24 at the forward face 25 of the plug element.

The rear portion 22 of the plug element 21; is provided with at least one inlet opening 27. The axis of the opening 27 is disposed in a chord or tangential position with respect to the cylindrical wall of the cavity as best shown in FIG. 3. Another inlet opening 27 may be provided in the rear portion of the body member 21 and its axis is in the same transverse plane as the first inlet opening and also disposed in a chord or tangential posi tion with respect to the cylindrical wall of the cavity 23. A generally annular space 28 is provided between the inner surface of the tubular member 18 the exterior surfaces of the rear portion 22 of the body member 21.

A source of liquid fuel under pressure is supplied into a pipe 31 which is connected to the rear portion of the tubular member 18. This connection may be made by means of threads having larger diameter than the threaded connection between the body member 21 the tubular member 18. The liquid fuel is supplied into the pipe 31 at pressures above atmospheric. A larger pipe is threaded into the rear end portion of the sleeve 1%- and an annular space 33 is provided between the exterior of the tubular member 13 and the interior of the pipe 3-2. This space is supplied with steam or compressed air at pressures equal to or greater than the pressure applied to the liquid fuel in the pipe 31.

One or more inlet holes for the steam or compressed air are provided through the tubular element 13. These holes 3d are disposed in a common transverse plane which are located downstream in the face 26 of the body member 21. In the embodiment shown in FIG. 4 three inlet holes 36 are provided through the tubular element 13 which are equally spaced circumferentially of the asset bly. Each of the inlet holes 36 is disposed with its axis in a chordal or tangential position with respect to the inner circumference of the tubular element 18.

The liquid fuel supplied under pressure into the pipe 31 enters the annular space 28 and passes inwardly through an opening 27. The liquid fuel is supplied under pressure and there is a drop in pressure across the opening 27 and the flow of the liquid is accelerated. The rapidly flowing liquid enters the cavity 23 and a tangential component is imparted to the liquid. The liquid fuel stream engages the cylindrical wall of the cavity 23 and spins or whirls circumferentially thereon as a film and moves in a generally helical path downstream from the opening or openings 27. As the film arrives at the downstream end of the cavity 23 it spins over the annular lip 24 in the form of a thin conical spray of small droplets. This condition is diagrammatically illustrated in FIG. 7. The liquid fuel is thereby broken into a multitude of tiny droplets Without action of mechanically moving parts so that the total surface area of the droplets is many times greater than that of the liquid fuel prior to emerging from the cavity 23. The steam or compressed air moves into the annular space 33 and passes through the holes 36. The steam or air entering through the holes 36 set up circumferential turbulence Within the chamber 37 to promote further atomization of the fuel particles whereby droplets of substantially uniform small size are produced. The circumferential movement of the steam or air serves to promote vaporization of the fuel droplets and serves to promote uniform distribution of the fuel mixture to the discharge ports 12.

The structure provides for pro-atomization of the liquid fuel before being subjected to the action of the steam or air. Such a step reduces the vaporization period and provides a gaseous fuel mixture which serves to provide stable burning operation over a wide turn down ratio.

A modification is shown in FIG. 6 wherein the holes 36a have their axes in a common plane but the axis of each is disposed in a radial position with respect to the axis of the tubular member 13. The operation and arrangement is similar to that described in connection with the device when the inlet ports for the steam or air are disposed in chordal or tangential positions with respect to the tubular member 13.

While the invention has been described with reference to specific structural features and with regard to one overall organization it will be appreciated that changes may be made in the various elements and in the combination of parts which provides pro-atomization of the liquid fuel prior to being delivered into the presence of the steam or air. Such changes and others may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

What I claim and desire to secure by Letters Patent is:

1. An assembly for vaporizing liquid fuel comprising, a nozzle having a chamber therein, said nozzle having a pattern of discharge ports in the end thereof, a tubular member engaging said nozzle in fluid tight relationship with the interior enlarging said chamber, a body member plugging the upstream portion of said tubular member, said body member having a cavity therein open at its downstream end into unobstructed communication with said chamber, a substantially cylindrical wall forming a major portion of said cavity, a surface on said body member forming an annular corner with said cylindrical wall at the downstream end thereof, said body member having an opening therethrough adjacent the upstream end thereof with its axis disposed substantially tangentially of said cylindrical Wall, means guiding liquid fuel under pressure greater than atmospheric through said opening whereby the liquid moves circumferentially and substantially helically as a film on said cylindrical wall over said corner and spills particles of liquid in a substantially frustoconical pattern, said tubular member having holes therethrough spaced downstream from said surface, means for supplying a gaseous medium under pressure equal to or greater than the pressure applied to the liquid fuel whereby the gaseous medium engages the fuel particles after they have been released from said cavity to promote further atomization 0f the fuel While confined within the tubular member and within said chamber, and said discharge ports being disposed to release the vaporized fuel as a fixed pattern through said discharge ports.

2. An assembly for vaporizing liquid fuel according to claim 1 wherein the holes in the tubular member are disposed with their axes substantially tangentially of the inner surface of the tubular member.

References Cited in the file of this patent UNITED STATES PATENTS 982,655 Albee Jan. 24, 1911 1,474,603 Morse Nov. 20, 1923 1,567,482 Anthony Dec. 29, 1925 1,594,641 Starr Aug. 3, 1926 2,325,495 Ferguson July 27, 1943 2,379,161 Kraps June 26, 1945 2,566,788 Berggren et al. Sept. 4, 1951 2,636,778 Michelson Apr. 28, 1953 FOREIGN PATENTS 662,651 Germany July 18, 1938 

1. AN ASSEMBLY FOR VAPORIZING LIQUID FUEL COMPRISING, A NOZZLE HAVING A CHAMBER THEREIN, SAID NOZZLE HAVING A PATTERN OF DISCHARGE PORTS IN THE END THEREOF, A TUBULAR MEMBER ENGAGING SAID NOZZLE IN FLUID TIGHT RELATIONSHIP WITH THE INTERIOR ENLARGING SAID CHAMBER, A BODY MEMBER PLUGGING THE UPSTREAM PORTION OF SAID TUBULAR MEMBER, SAID BODY MEMBER HAVING A CAVITY THEREIN OPEN AT ITS DOWNSTREAM END INTO UNOBSTRUCTED COMMUNICATION WITH SAID CHAMBER, A SUBSTANTIALLY CYLINDRICAL WALL FORMING A MAJOR PORTION OF SAID CAVITY, A SURFACE ON SAID BODY MEMBER FORMING AN ANNULAR CORNER WITH SAID CYLINDRICAL WALL AT THE DOWNSTREAM END THEREOF, SAID BODY MEMBER HAVING AN OPENING THERETHROUGH ADJACENT THE UPSTREAM END THEREOF WITH ITS AXIS DISPOSED SUBSTANTIALLY TANGENTIALLY OF SAID CYLINDRICAL WALL, MEANS GUIDING LIQUID FUEL UNDER PRESSURE GREATER THAN ATMOSPHERIC THROUGH SAID OPENING WHEREBY THE LIQUID MOVES CIRCUMFERENTIALLY AND SUBSTANTIALLY HELICALLY AS A FILM ON SAID CYLINDRICAL WALL OVER SAID CORNER AND SPILLS PARTICLES OF LIQUID IN A SUBSTANTIALLY FRUSTOCONICAL PATTERN, SAID TUBULAR MEMBER HAVING HOLES THERETHROUGH SPACED DOWNSTREAM FROM SAID SURFACE, MEANS FOR SUPPLYING A GASEOUS MEDIUM UNDER PRESSURE EQUAL TO OR GREATER THAN THE PRESSURE APPLIED TO THE LIQUID FUEL WHEREBY THE GASEOUS MEDIUM ENGAGES THE FUEL PARTICLES AFTER THEY HAVE BEEN RELEASED FROM SAID CAVITY TO PROMOTE FURTHER ATOMIZATION OF THE FUEL WHILE CONFINED WITHIN THE TUBULAR MEMBER AND WITHIN SAID CHAMBER, AND SAID DISCHARGE PORTS BEING DISPOSED TO RELEASE THE VAPORIZED FUEL AS A FIXED PATTERN THROUGH SAID DISCHARGE PORTS. 